Re: Breaking a table of record rows into an array

On 2024-03-13, Keith Thompson <Keith.S.Thompson+u@gmail.com> wrote:

That describes what happens if NF is modified by assignment, but I don't
see that it implies that such an assignment is allowed.

Here is a problem. In numerous implementations, when you set NF, not
only does that set the number of fields, but $0 is recomputed.
So instead of $1=$1 you can use NF=NF.

  $ echo '1 2 3 4' | awk -v OFS=: '{ NF=NF; print $0; }'
  1:2:3:4

  $ echo '1 2 3 4' | awk -v OFS=: '{ NF=2; print $0; }'
  1:2


We can continue to infer that if setting NF causes certain fields to
exist, and not others, then $0 must be reconstituted accordingly,
just like when a field is assigned, according to the idea that Awk
implements a kind of "reactive programming" paradigm whereby $0
and the fields are kept in sync.

But that's going a little unconfortably far on the proverbial limb,
without assurance from the text.

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